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Return Option<T> instead of erroring with api::Error:::KeyNotFound #171

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merged 1 commit into from
Jul 28, 2023
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Return Option<T> instead of erroring with api::Error:::KeyNotFound #171

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11 changes: 6 additions & 5 deletions firewood/src/v2/api.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -62,8 +62,6 @@ pub enum Error {
provided: HashKey,
current: HashKey,
},
/// Key not found
KeyNotFound,
IO(std::io::Error),
InvalidProposal,
}
Expand Down Expand Up @@ -131,10 +129,13 @@ pub trait DbView {
async fn root_hash(&self) -> Result<HashKey, Error>;

/// Get the value of a specific key
async fn val<K: KeyType>(&self, key: K) -> Result<Vec<u8>, Error>;
async fn val<K: KeyType>(&self, key: K) -> Result<Option<Vec<u8>>, Error>;

/// Obtain a proof for a single key
async fn single_key_proof<K: KeyType, V: ValueType>(&self, key: K) -> Result<Proof<V>, Error>;
async fn single_key_proof<K: KeyType, V: ValueType>(
&self,
key: K,
) -> Result<Option<Proof<V>>, Error>;

/// Obtain a range proof over a set of keys
///
Expand All @@ -149,7 +150,7 @@ pub trait DbView {
first_key: Option<K>,
last_key: Option<K>,
limit: usize,
) -> Result<RangeProof<K, V>, Error>;
) -> Result<Option<RangeProof<K, V>>, Error>;
}

/// A proposal for a new revision of the database.
Expand Down
6 changes: 3 additions & 3 deletions firewood/src/v2/db.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -72,14 +72,14 @@ impl api::DbView for DbView {
todo!()
}

async fn val<K: KeyType>(&self, _key: K) -> Result<Vec<u8>, api::Error> {
async fn val<K: KeyType>(&self, _key: K) -> Result<Option<Vec<u8>>, api::Error> {
todo!()
}

async fn single_key_proof<K: KeyType, V: ValueType>(
&self,
_key: K,
) -> Result<api::Proof<V>, api::Error> {
) -> Result<Option<api::Proof<V>>, api::Error> {
todo!()
}

Expand All @@ -88,7 +88,7 @@ impl api::DbView for DbView {
_first_key: Option<K>,
_last_key: Option<K>,
_limit: usize,
) -> Result<api::RangeProof<K, V>, api::Error> {
) -> Result<Option<api::RangeProof<K, V>>, api::Error> {
todo!()
}
}
37 changes: 17 additions & 20 deletions firewood/src/v2/emptydb.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -54,21 +54,24 @@ impl DbView for HistoricalImpl {
Ok(ROOT_HASH)
}

async fn val<K: KeyType>(&self, _key: K) -> Result<Vec<u8>, Error> {
Err(Error::KeyNotFound)
async fn val<K: KeyType>(&self, _key: K) -> Result<Option<Vec<u8>>, Error> {
Ok(None)
}

async fn single_key_proof<K: KeyType, V: ValueType>(&self, _key: K) -> Result<Proof<V>, Error> {
Err(Error::KeyNotFound)
async fn single_key_proof<K: KeyType, V: ValueType>(
&self,
_key: K,
) -> Result<Option<Proof<V>>, Error> {
Ok(None)
}

async fn range_proof<K: KeyType, V: ValueType>(
&self,
_first_key: Option<K>,
_last_key: Option<K>,
_limit: usize,
) -> Result<RangeProof<K, V>, Error> {
Err(Error::KeyNotFound)
) -> Result<Option<RangeProof<K, V>>, Error> {
Ok(None)
}
}

Expand All @@ -91,12 +94,9 @@ mod tests {

let proposal = db.propose(batch).await?;

assert_eq!(proposal.val(b"k").await.unwrap(), b"v");
assert_eq!(proposal.val(b"k").await.unwrap().unwrap(), b"v");

assert!(matches!(
proposal.val(b"z").await.unwrap_err(),
Error::KeyNotFound
));
assert!(matches!(proposal.val(b"z").await.unwrap(), None));

Ok(())
}
Expand Down Expand Up @@ -126,20 +126,17 @@ mod tests {
.await?;
let proposal2 = Arc::new(proposal2);
// both proposals still have (k,v)
assert_eq!(proposal1.val(b"k").await.unwrap(), b"v");
assert_eq!(proposal2.val(b"k").await.unwrap(), b"v");
assert_eq!(proposal1.val(b"k").await.unwrap().unwrap(), b"v");
assert_eq!(proposal2.val(b"k").await.unwrap().unwrap(), b"v");
// only proposal1 doesn't have z
assert!(matches!(
proposal1.val(b"z").await.unwrap_err(),
Error::KeyNotFound
));
assert!(matches!(proposal1.val(b"z").await.unwrap(), None));
// proposal2 has z with value "undo"
assert_eq!(proposal2.val(b"z").await.unwrap(), b"undo");
assert_eq!(proposal2.val(b"z").await.unwrap().unwrap(), b"undo");

// create a proposal3 by adding the two proposals together, keeping the originals
let proposal3 = proposal1.as_ref() + proposal2.as_ref();
assert_eq!(proposal3.val(b"k").await.unwrap(), b"v");
assert_eq!(proposal3.val(b"z").await.unwrap(), b"undo");
assert_eq!(proposal3.val(b"k").await.unwrap().unwrap(), b"v");
assert_eq!(proposal3.val(b"z").await.unwrap().unwrap(), b"undo");
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I just follow the pattern, but if it was up to me I would just change it to assert_eq!(proposal3.val(b"z").await, Ok(Some(b"undo")));.

Also, it think it would be nice to use bytes::Bytes instead of raw Vec<u8> (

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We eventually will be returning a reference instead of an owned value, but we want to get something out soon so we're sticking with owned for now and will change that later.

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The beauty of bytes::Bytes is that you can return the ownership but the memory segment is referenced counted internally[1].

People are free to copy into a bytes::BytesMut to modify, but bytes::Bytes are read only.

[1] https://docs.rs/bytes/latest/bytes/#bytes


// now consume proposal1 and proposal2
proposal2.commit().await?;
Expand Down
10 changes: 5 additions & 5 deletions firewood/src/v2/propose.rs
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Expand Up @@ -102,13 +102,13 @@ impl<T: api::DbView + Send + Sync> api::DbView for Proposal<T> {
todo!()
}

async fn val<K: KeyType>(&self, key: K) -> Result<Vec<u8>, api::Error> {
async fn val<K: KeyType>(&self, key: K) -> Result<Option<Vec<u8>>, api::Error> {
// see if this key is in this proposal
match self.delta.get(key.as_ref()) {
Some(change) => match change {
// key in proposal, check for Put or Delete
KeyOp::Put(val) => Ok(val.clone()),
KeyOp::Delete => Err(api::Error::KeyNotFound), // key was deleted in this proposal
KeyOp::Put(val) => Ok(Some(val.clone())),
KeyOp::Delete => Ok(None), // key was deleted in this proposal
},
None => match &self.base {
// key not in this proposal, so delegate to base
Expand All @@ -121,7 +121,7 @@ impl<T: api::DbView + Send + Sync> api::DbView for Proposal<T> {
async fn single_key_proof<K: KeyType, V: ValueType>(
&self,
_key: K,
) -> Result<api::Proof<V>, api::Error> {
) -> Result<Option<api::Proof<V>>, api::Error> {
todo!()
}

Expand All @@ -130,7 +130,7 @@ impl<T: api::DbView + Send + Sync> api::DbView for Proposal<T> {
_first_key: Option<KT>,
_last_key: Option<KT>,
_limit: usize,
) -> Result<api::RangeProof<KT, VT>, api::Error> {
) -> Result<Option<api::RangeProof<KT, VT>>, api::Error> {
todo!()
}
}
Expand Down
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